In designing various automobiles, designers seek to make particular mechanical systems have a particular robustness, such as a designed safety factor or a design parameter range that will allow for variations in manufactured parts. In order to achieve these values, designers typically select a predetermined figure or robustness factor that the system is sought to achieve. The components of the mechanical system are then designed in order to achieve this predetermined robustness value. In various instances, the predetermined robustness values used in designing vehicles can be a somewhat arbitrary number based upon older designs.